This invention relates generally to apparatus and method for determining temperatures at well heads, and more particularly to sensing of changes in temperatures at or proximate well pump polish rods, and to sensing of well fluid leakage at the well head.
The majority of oil wells which are pumped, as contrasted to those flowing as a result of internal pressure, employ a deep well pump connected by sucker rods to a driving mechanism on the earths' surface at the well head. The top-most link in this connecting system is known as the polish rod because it slides up and down through a sealing gland, called a stuffing box, at the well head. The polish rod, because of its location on the sucker rod string, is accessible to temperature measurement. Further its temperature reflects conditions relative to the operation of the well, such as:
(a) The tightness of the sealing gland; PA1 (b) The presence or lack of well fluid at the top of the well; PA1 (c) The increase in well fluid temperature when not flowing (as in pump off); and PA1 (d) The leakage of well fluid past the wellhead seal. PA1 (a) first means located in proximity to the polish rod to sense its temperaturs T.sub.1, PA1 (b) second means for sensing temperature T.sub.2 of the environment near the well head, PA1 (c) and circuitry operatively connected to said first and second means to provide an output signal which is a function of the difference between T.sub.1 and T.sub.2.
Although temperature changes in or of the polish rod may be relatively slight as in the case of the above mentioned conditions, the change of temperature will be a significant amount relative to the difference in temperature of the rod and its environment. This change in temperature difference can be used to diagnose problems in well or pump operation, to provide warnings which will permit avoidance of continued operation under adverse conditions, and to effect changes in well control, these being needs which exist in operation of wells.